Electric motor and brake.



No. 828,528. PATENTED AUG. 14, 190e. H. A. BALGOMB.

ELECTRIC MOTOR AND BRAKE.

APPLICATION HLBD N0v.3o,1904,

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THE Namur! PETERs co., wAsHlNcraN. D; c.

NITEI) STATES PATENT OFFICE.

HERBERT A. BALCOME, OF BOSTON, MASSACHUSETTS, ASSIGNOR B. E. STUBTEVANT COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORA- TION OF MASSACHUSETTS.

ELECTRIC MOTOR AND BRAKE.

Specification of Letters Patent.

Patented Aug. 14, 1906.

Application filed November 30, 1904. Serial No. 234,884.

To all whom it may concern:

Be it known that I, HERBERT A. BALcoME, a citizen of the United States, residing at J amaica Plain, Boston, in the county of Suifolk and State of Massachusetts, have invented certain new and useful Improvements in Electric Motors and Brakes and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to an improvement in electric motors, and more particularly to electric motors provided with automatic electromagnetic brakes.

It is desired in many uses of electric motors to provide means for applying a brake to the armature when the motor is stopped either by intention or by accidental means,

such as the breaking` of the circuit which drives the motor.

To this end the object of the present invention is to produce an electric motor provided with braking mechanism operating to apply the brake when the motor is stopped; and the invention consists in the devices and combinations of devices hereinafter described and claimed.

In the accompanying drawings, illustrating the preferred form of the invention, Figure 1 is an elevation, principally in section, of an electric motor provided with the braking mechanism of the invention; and Fig. 2 is a section taken on the line a: x, Fig. 1, looking in the direction of the arrow.

The motor consists of a frame 1, provided With heads 2 and 3, which carry the bearings for the shaft of the armature 4. The armature-core 5 is provided in one end with a space 6, which is incidental to the form ofthe armature in the type of motor illustrated. This space in motors of this type as they have been heretofore constructed has been unoccupied, and it is proposed according to the present invention to place the braking mechanism within this space. Two frictionbrake members are secured to the armatureshaft in the space 6, above referred to. The brake member 7, consisting of a disk with a laterally-projecting iiange, is secured by means of screws to the core 5 of thearmature, and the brake member 8 is similarly secured by means of screws to the projecting flange of the armature-core 5. Between these two friction-brake members is located the electromagnetic braking mechanism, which consists of a magnet and a brake armature provided with braking surfaces to cooperate with the above-described frictionbrake members. The magnet consists of -a hollow ring-shaped body 9, within the annular space of which is received the magnetic coil 10. The magnet-body 9 is supported upon a sleeve 1 1, which -is secured to the head 3 of the motor. The magnet-body 9 is longitudinally movable upon the said sleeve, but splined thereto in order to hold it rotatively stationary. The coil 10 is covered bya coverplate 12, of insulating or non-magnetic material, such as fiber, recessed into the face of the magnet-body. The brake-armature 13 is a disk, corresponding in size to the magnetbody, which is mounted upon the sleeve 11 and held from rotation thereon by means of pins 14, which project from holes in the magnet-body into holes in the brake-armature. The pins 14 are normally pressed into engagement with the brake-armature by means of springs behind them. The magnet-body and armature comprise two movable and rotatably stationary friction-brake members adapted, respectively, to engage the brake members secured to the armature-shaft. The vabove-described construction is such that when the coil 10 is energized by a current it attracts the armature 13 and compresses the springs 15, supporting the pins 14, pulling the magnet-body and armature toward each other and out of contact with the friction members upon the armatureshaft. Thus the brake is released when the magnet is energized.

It will be noted that the springs normally operate to apply the brake and that the magnet comprises electromagnetic means for collapsing the movable brake members and releasing the brake. The movable brake members oppose each other. They thrust against each other and against the brake members upon the armature-shaft, and thus apply the brake without exerting any force upon the armature tending to move it endwise in its bearings.

It will be observed that the construction IOO lbecause this is the construction of a type of armature which obtains in general use and which is particularly adapted for this pur pose.

Having thus described the invention, what is claimed is- 'l 1. An electric motor, having, in combination, an armatui'e having a space therein, its

shaft, and a friction-brake located in said space in the armature, substantially as described.

2. An electric motor, having, in combination, an. armature having a space therein, its shaft, and a 'friction-brake and electromagnetic means Alor operating the brake located in said space in the armature, substantially as described.

3. An electric motor, having, in combination, an armature, its shaft, two opposed 'friction-brake members secured to the armature-shaft, two movable rotatively stationary 'friction-brake members located between said opposed brake members, a spring 'for forcing said last-named brake members into contact with the armature-brake members, and electromagnetic means vfor collapsing the movable brake members, substantially as described.

4. An electric motor, having, in combination, an armature, its shaft, two opposed rfriction-brake members secured to the armature-shaft, two movable brake ,members located between the armature-brake membei's, and spring and electromagnetic operating mechanism for the movable brake members, substantially as described.

5. An electric motor, having, in combination, a casing, an armature journaled therein and provided 'with a' brake-surface, a coperating brake member located between the armature and the end of the casing and prevented l'rom rotation by connection with the casing, and electromagnetically-controlled means 'for moving the brake-surfaces into operative contact, substantially as described.

6. An electric motor, having, in. combination, a casing, an armature journaled therein and provided with an annular recess, oppositely disposed conical brake surfaces located in the recess and 'fixed to the armature, an expanding electromagnetically-controlled brake located in the recess and having oppositely-disposed brake-surfaces for coperating with the brake-surfaces on the armature, and connections between the casing and the brake to prevent rotation of the latter, substantially as described.

7. An electric motor, having, in combination, a casing, a shaft journaled therein, a sleeve iixed to one end ol the casing and projecting inwardly, and annular with respect to the shaft, two brake members mounted on the sleeve 'free to move longitudinally thereon. but not to rotate, an. armature mounted on the shalt within the casing and provided with an annular portion surrounding the brake members, two oppositely-disposed brake members lixed to the said annular portion of the armature, springs normally tending to 'force the non-rotary brake members into contact with the rotary brake members, and a magnet located within the casing for drawing the brake members out of' contact, substantially as described.

In testimony whereof I ailiX my signature in presence of two witnesses` HERBERT A. BALCOME.

/Vitnesses:

HORACE VAN EVEREN, FARNUM F. DoRsEY. 

